1. Field of the Invention
The present invention relates to a maintenance method for use in a liquid ejecting apparatus such as an ink jet printer, and an ink jet printer.
2. Description of the Related Art
Liquid ejecting apparatuses have liquid ejecting heads capable of ejecting liquids as droplets, and eject various types of liquids from the ejecting heads.
Examples of typical liquid ejecting apparatuses include an image recording apparatus, such as an ink jet printer, having an ink jet recording head (hereinafter referred to simply as a recording head) as a liquid ejecting head, for performing recording by forming dots in such a manner that liquid ink is allowed to be discharged as ink droplets from nozzles (openings) of the recording head and to land on a discharge target such as recording paper.
In recent years, the liquid ejecting apparatuses have been applied not only to the image recording apparatuses but also to various manufacturing apparatuses such as an apparatus for manufacturing color filters of liquid crystal displays, etc.
In such an image recording apparatus, for example, ink stored in a liquid reservoir such as an ink tank or an ink cartridge is introduced into a pressure chamber of a recording head, and a driving signal is applied to drive a pressure generating source such as a piezoelectric vibrator, whereby a pressure change is caused to occur in the ink in the pressure chamber. By controlling the pressure change, an ink droplet can be discharged from a nozzle.
Regarding the recording head, on the basis of a driving voltage (potential difference from the lowest voltage to the highest voltage) of the driving signal supplied to the pressure generating source and a waveform thereof, a liquid amount (weight and volume) of an ink droplet discharged from the nozzle increases or decreases.
In a liquid ejecting apparatus, in order that each nozzle of the recording head may be maintained in a good state and that missing dots may be prevented from occurring in such a manner that a desired amount of ink droplets is always discharged, in a case such as before the start of recording (printing), during recording, or after finishing recording, so-called flushing processing in which, by discharging ink from each nozzle, ink having increased viscosity, etc., in the nozzle is discharged is performed
The liquid discharged by the flushing processing collects in a tray-shaped liquid receiver. When a predetermined amount of the liquid has collected in the liquid receiver, a pump is driven to discharge the liquid to a discharge ink tank. This processing is called idle suction processing (Japanese Unexamined Patent Application Publication No. 2006-248132).
The liquid that collects in the liquid receiver needs to be discharged before overflowing the liquid receiver. However, since the amount of the liquid that collects in the liquid receiver cannot be directly measured, conventionally, the amount of the liquid that collects is indirectly determined on the basis of the amount of the liquid discharged from the nozzle of the recording head and the number of times discharging has been performed. At this time, the liquid amount discharged from the nozzle changes according to environmental conditions such as temperature and humidity, and the liquid amount varies. Thus, the liquid amount is determined assuming the worst conditions (a case where the liquid amount is the largest).
In addition, to ensure avoidance of liquid leaking from the liquid receiver, at the time the amount of the liquid that is collecting has reached a predetermined liquid amount less than the volume (for example, approximately 80% of the volume of the liquid receiver) of the liquid receiver, the pump is driven. In addition, the volume of the liquid receiver is determined assuming that, when a liquid absorber disposed in the liquid receiver is used, the liquid absorber is clogged.
Accordingly, even if the liquid receiver can still sufficiently store liquid, the pump is driven. In other words, there is a problem in that a frequency of pump driving increases.
In particular, in a case where a driving motor for a pump for discharging (suction) liquid from the liquid receiver is also used as a driving motor for a paper feeding mechanism for feeding and expelling recording paper to a recording head, when liquid is discharged from the liquid receiver, it is necessary to interrupt recording processing including paper feeding and expelling. Thus, there is a problem in that efficiency of the recording processing decreases.